A variety of insulation materials have been proposed for abating sound and thermal transmission from a source thereof to some protected area or enclosure. For example, insulation materials can be used to abate sound or thermal transmission through the walls and ceilings of houses, buildings and the like; from appliances, such as washing machines, refrigerators, and dishwashers; from the exterior of vehicles, such as automobiles, airplanes, trains, and ships; from machinery, such as presses, compressors, blowers, and HVAC systems; and from tanks, storage vessels, pipes and duct work.
The use of glass fiber blowing-wool or loose-fill insulation is well-known and increasing in popularity for thermal insulation. Loose-fill insulation is preferred by many contractors because it can be easily and quickly applied in both new construction, a well as in existing structures. Further, loose-fill insulation is a relatively low-cost material.
As the name implies, loose-fill insulation is not formed into a blanket or batt prior to installation. Rather, the product is generally installed by pneumatically blowing the loose-fill insulation into the desired area. Accordingly, loose-fill insulation in an unconstrained space, such as an attic, is not as compacted as blanket insulation, occupying a greater volume than an equivalent amount of blanket insulation. As a result, the thermal resistance or R value of loose-fill insulation is generally lower than that of blanket insulation. That is, loose-fill insulation currently used in the industry does not prevent the conduction of heat as well as blanket insulation. To compensate for the higher conductivity of loose-fill, it is applied in greater depth than blanket insulation to achieve an equivalent R-value.
When designing loose-fill or blown insulation products of glass fibers, the ideal insulation would have uniform spacing and density once installed. Insulation is basically a lattice for trapping air between the fibers and thus preventing movement of air. The lattice also retards heat transfer by scattering radiation. A more uniform spacing and density would minimize air movement and maximize scattering and, therefore, would have greater insulating capability.
Traditional loose-fill or blown insulation comprises straight or short fibers. Batts of bindered or unbindered glass fibers are cut, compressed and bagged for shipment. Upon installation, the compressed loose-fill is added to the hopper of a blower where the loose-fill is mechanically recovered and broken into smaller portions. After being blown into position, numerous small gaps or voids remain between the blown portions of insulation. These voids raise the thermal conductivity of the insulation requiring more glass to be employed to achieve a specified insulating value, or result in a shortfall in insulating value. Further, the blown insulation includes relatively ineffective insulating flakes or wads of the insulation incorporated into the blown insulation. These flakes or wads add significantly to the density of the insulation, in essence increasing the amount of glass used relative to its insulating value.